Luminaires with automated and remotely controllable functionality are well known in the entertainment and architectural lighting markets. Such products are commonly used in theatres, television studios, concerts, theme parks, night clubs and other venues. A typical product will commonly provide control over the pan and tilt functions of the luminaire allowing the operator to control the direction the luminaire is pointing and thus the position of the light beam on the stage or in the studio. Typically this position control is done via control of the luminaire's position in two orthogonal rotational axes usually referred to as pan and tilt. Many products provide control over other parameters such as the intensity, color, focus, beam size, beam shape, beam framing, and beam pattern. The luminaire may be capable of producing a diffused, non-imaging, field of light, often called a wash luminaire, or may be capable of producing a defined image in the light beam, often called a spot luminaire. Other products may be capable of both wash and spot operation. The products manufactured by Robe Show Lighting are typical of the art.
The optical systems of such luminaires may include a gate or aperture through which the light is constrained to pass. Mounted in or near this gate may be devices such as gobos, patterns, irises, color filters or other beam modifying devices as known in the art. The use of a framing shutter system at this point allows control over the size and shape of the output beam and thus the size and shape of the image projected onto a surface.
FIG. 1 illustrates an example of a prior art multiparameter automated luminaire system 10. These systems commonly include a plurality of multiparameter automated luminaires 12 which typically each contain on-board a light source (not shown), light modulation devices, electric motors coupled to mechanical drive systems and control electronics (not shown). In addition to being connected to mains power either directly or through a power distribution system (not shown), each automated luminaire 12 is connected is series or in parallel to data link 14 to one or more control desks 15. The automated luminaire system 10 is typically controlled by an operator through the control desk 15.
Although many of the lighting controls and effects available to conventional, non-automated, luminaires have been adapted for use with fully automated units, the use of a scrim, or half-scrim, has not so far been offered to the users of automated luminaires. A scrim, as used in conventional luminaires, is a means for adjusting the intensity of portions of a light beam in a selective manner. In some prior art luminaires it comprises a fine metal mesh screen that is placed on the front of a luminaire to act as a dimmer. The position of the mesh may be adjusted so as to selectively dim portions of the output light beam, while leaving other areas unaffected. Similarly, the density of the mesh may be chosen based on the amount of light dimming produced. Scrims are also available in the prior art for conventional luminaires such that only half of the output beam is screened, therefore allowing for only a portion of the light beam to be dimmed. This allows the operator to selectively control the light level across a light beam as well as control the overall intensity using a normal dimmer.
A scrim in a conventional luminaire may be used to grade the light output across a cyclorama in a theatre, or in a television or film studio, to modulate the light intensity across two or more performers. For example, it is very common in television lighting to have two performers in a single shot such as in an interview or talk show situation. In those circumstances there will likely be two crossing key lights, one lighting the face of each performer. A side effect of such a lighting set up is that the key light for the face of performer A will also illuminate the back of the head of performer B, and vice versa. To reduce this unwanted illumination of the backs of the performer's heads, each of the two crossing key lights may be fitted with a scrim in the lower half of the beam to reduce the intensity of the light beams solely in the areas where they illuminate the wrong performer while retaining the intensity of the light beam in the area where it illuminates the face of the intended performer.
Such functionality has not been available in automated luminaires; however, automated luminaires are increasingly used in these areas of lighting. Thus, there is a need for a controllable scrim system for an automated luminaire which provides the user with both accurate positioning and the ability for rapid movement.